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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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vol_300
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342_01
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diofnc10.c
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1991-02-25
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/*-
* ----------------------------------------------------------------------
* File : DIOFNC10.C
* Creator : Blake Miller
* Version : 01.01.00 February 1991
* Language : Microsoft Quick C Version 2.0
* Purpose : Intel 8255 Compatible Digital IO Functions
* 80X86 IN Instruction Function
* ----------------------------------------------------------------------
* WARNING: Inline Assembly Language Here!
* ----------------------------------------------------------------------
* Revision History:
* 022891 BVM : Change int to short.
* 070490 BVM : Creation
* ----------------------------------------------------------------------
*/
#define DIOFNC10_C_DEFINED 1
#undef DIOFNC10_C_DEFINED
void dio_bget (short d_port, unsigned char *d_byte);
/*- DIO : Byte Get ---------------------------**
* Read a byte from one of the 80X86 ports.
* Duplicates the library function inp()
*/
void dio_bget (short d_port, unsigned char *d_byte)
{
unsigned char t_byte = 0; /* temporary byte */
/* set port address
* get data into AL
* store data into temporary variable
* Note: Use temporary variable because ASM has no idea
* what a pointer to an unsigned char is!
*/
_asm {
PUSH AX
PUSH DX
MOV DX, d_port
IN AL, DX ; get byte into AL
MOV t_byte, AL ; transfer data to C
POP DX
POP AX
}
*d_byte = t_byte; /* transfer data to caller */
}
/*-
* ----------------------------------------------------------------------
* END DIOFNC10.C Source File
* ----------------------------------------------------------------------
*/